Omg same!! I thought it was just me!!! God damn it... I shouldn't have added anything new cuz my list stopped adding back mangas midway too... it's been 2 days already Is this it?!? Pls no!!! I regret it so much god I thought since my list was getting updated it was back to normal... is it possible to fix this particular issue?!
Nah don't worry, it doesn't affect the process. Many says we need to wait for at least 2 weeks for our list to comeback fully recovered. I'm even starting to add new now reading list.
Here for more info:
https://www.mangago.me/home/mangatopic/21080691/
https://www.mangago.me/home/mangatopic/21092806/

Damn my already read came back except like 16 are missing (I have a screenshot of my entire list prior to The Great Reset) and my reading was coming back slowly but I added something stupidly and it hasn't updated since I'm scared I broke it and they wont come back now it used to update every few hours but it completely stopped since I added something new